FOXBOROUGH, Mass.—Win or lose, chances are you’re going to hear the same post-game analysis from New England Patriots coach Bill Belichick. It usually involves doing some things well and needing to do a whole lot better.

But after Sunday’s 20-18 stunning loss to the Arizona Cardinals at Gillette Stadium, Belichick’s assertion that, “We need to coach better, we need to play better, we need to do better than that,” seemed particularly accurate.

It was New England's first loss in a home opener at Gillette Stadium since it opened in 2002.

The Patriots fell on Stephen Gostkowski's hooked field-goal try from 42 yards with 6 seconds on the clock. In reality, the seeds of this loss were sown by Belichick and the team’s front office (which basically means Belichick) long before that errant kick.

This isn’t to denigrate Belichick’s accomplishments. Nor is it to overlook how well the Cardinals' defense played. But there are a few things that unfolded Sunday that could be long-range concerns for New England this season and they all circle back to Belichick.

There's the injury suffered by Aaron Hernandez in the first quarter. Hernandez rolled his ankle rolled while blocking for surprise starter Julian Edelman. While Belichick didn't say what Hernandez’s status would be, the Patriots' tight end left the game on crutches in a boot, an indication it's at least a severe sprain. On a day in which the offense sputtered, Hernandez’s injury was a big reason.

But, as quarterback Tom Brady said, “We have an offense with him in the game and an offense without him in the game. Guys go in and out and you lose guys over the course of a game and you’ve gotta be able to adjust. I am sure he's not going to be the only one we lose this year at some point, but we still have to figure out a way to still move the ball effectively throughout the course of a game enough to where we can score more than 18 points.”

That's especially disappointing for New England. The Patriots brought back boy genius (ahem) offensive coordinator Josh McDaniels, who's probably right to reconfigure New England’s offense around the dynamic tight end duo of Hernandez in a hybrid role and Rob Gronkowski. But the team still has Wes Welker as one of the best slot receivers in the game, and Brandon Lloyd (eight catches) on the outside. Throw in the impressive play of second-year back Stevan Ridley, and there are still plenty of options for Brady.

Yet, despite 90 yards from Welker, the focus afterward was a “Where’s Wes?” parlor game trying to explain why the team chose to limit Welker’s place in the offense.

Even with Hernandez out, McDaniels and Belichick were slow to fall back on the hurry-up, three-receiver offense that's been a staple of Brady’s success. The Patriots ran it almost out of necessity in the fourth quarter, and nearly pulled off the comeback because of it.

When they scour the waiver wire to replace Hernandez, they’re likely to bring back one of the recently cut receivers—Deion Branch or Jabar Gaffney. That will put more emphasis on returning to a three-receiver offense. McDaniels will have to adjust better in the long term than he did Sunday.

But look closely at how things went against the Cardinals, and it wasn’t just the Hernandez injury that hurt the Patriots. Just as damaging was the injury to right guard Dan Connolly. That's saying something because Connolly should be a backup.

Without Connolly at guard, the Patriots had to start Donald Thomas, who was a disaster. He was unable to keep up with Cardinals star Darnell Dockett (his tipped pass led to an interception). Thomas also committed a key penalty and was partly responsible for the Cardinals' four sacks. New England has enough concern on the line with inconsistent second-year left tackle Nate Solder. Brady doesn't need to worry about more holes on the line.

Again, this comes back to Belichick. The Patriots hoped to rework the contract of guard Brian Waters, who's at the end of his career. Waters is still a potential Hall of Famer who wouldn't have been so easily duped by Dockett at the point of attack. Waters never showed up for camp, though. Whether it was because he reportedly didn’t like that the Patriots were nickel-and-diming him, or whether it was because he wanted to spend more time with his family, Belichick had to know.

With Matt Light's retirement, beefing up the line should have been a priority. Thomas is not the answer, and now Brady looks uncharacteristically antsy in the pocket.

This is all correctable, of course, and maybe it should have been expected considering the upheaval the Patriots are undergoing offensively. The line—especially Solder—should improve and give Brady a little more comfort. The offense should run smoother with a week to adjust to Hernandez’s absence and will have little choice but to re-integrate Welker in the meantime.

But that's going to depend on the coaches. With a revamped defense and Ridley at running back, the Patriots could have a better, more-balanced team than last year's Super Bowl finalist. Credit Belichick for bolstering the roster that way. But if the Patriots can’t put together wins, if they falter and underperform the way they did Sunday, the blame belongs with Belichick, too.